Methods for stabilizing and raising foundation structures



T R. FREEMAN, JR

Filed Oct. '7, 1963 Aug. 30, 1966 METHODS FOR STABILIZING AND RAISING FOUNDATION STRUCTURES INVENTOR THOMAS RICHARD FREEMANJR COR M P M ATTORNEYS FIG.7.

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United States Patent 3,269,126 METHODS FOR STABILIZING AND RAISlNG FOUNDATION STRUCTURES Thomas R. Freeman, Sin, 3338 Marmary Lane, St. Ann, Mo. Filed Oct. 7, 1963, Ser. No. 314,459 Claims. (Cl. 6151) This invention relates to improvements in means and methods for stabilizing and raising foundation structures which have dropped or shifted, usually as a result of weak and unstable subsoil conditions.

The present invention relates to improvements in the methods described in US. Patent No. 2,378,995 and involves the formation of a concrete column below and in supporting relationship to a foundation structure, and the injection of a hard-setting plastic composition into the ground at the base of the column.

The chief object and purpose of the invention is to provide a simple, inexpensive and highly satisfactory method for raising or restoring to an original location foundations which have become displaced due to faulty subsoil conditions; to stabilize such a foundation by the provision, with a minimum of trouble and expense, firm and durable underpinning that will fix the foundation permanently in its normal or restored position.

An object of the present invention is-to provide an improved method for shoring a wall or the like by castin g a concrete column in place in supporting relation thereto, and thereafter in forming an enlarged base or footing for the column.

An object is to provide an improved method for raising and stabilizing foundation structures where sandy loam, a mud seam, water pocket or other subterranean condition below the structure affords inadequate support.

The foregoing and other objects and advantages are achieved in an improved method wherein the hollow concrete beam is cast in place in the earth, with a space remaining directly below the column for the formation of a base or footing; injection, under high pressure, of a plastic, hard-setting material to fill and expand the space below the column, whereby to provide an enlarged base portion or footing for the column.

In the drawing:

FIG. 1 is a sectional view of a foundation wall and the means and methods of the present invention for raising and stabilizing the same; FIG. 2 is a plan view of the installation of FIG. 1, showing the manner in which a plurality of columns may be pumped simultaneously;

FIG. 3 is an enlarged sectional view illustrating in detail the means employed in the formation of the footing at the base of the column;

FIG. 4 is a sectional view taken at line 4-4 of FIG. 3;

FIG. 5 is a sectional view, similar to FIG. 1, illustrating additional provisions which may be employed where certain adverse soil conditions are encountered;

FIG. 6 is a sectional view taken at line 6-6 of FIG. 5, and

FIG. 7 is a vertical section showing details of the means employed in connection with the provisions illustrated in FIG. 5.

Describing now the means and method of my invention in detail, numeral designates a foundation wall with footing 11, and is representative of any foundation structure which is required to be stabilized or raised. In carrying out the present invention a hole is bored in the ground closely adjacent the foundation wall, as by means of an earth auger, to reach downwardly to rock or other strata having favorable load bearing qualities. A bore of from 8 to 12 inches in diameter has been found generally suitable for the purposes hereof. Where a wall or other extended structure is to be raised or stabiiized a plurality of such bores, suitably spaced along the wall as shown in FIG. 2, may be provided. In every instance the holes 12 should be continued through weak soil, porous or fissured strata, indicated at 13, to a solid. layer 14. An opening 15 is formed immediately below the foundation footing as a lateral off-set of hole 12, this being accomplished by suitable digging tools. Such may require a further enlargement of hole 12 at its upper end, as indicated at 15a.

In the hole there is cast a concrete column having an integral shoulder 30. Of importance to the present invention is the allowance of a substantial space directly below the column proper for the subsequent formation of an enlarged footing or base for the column. Also, the column is formed with a longitudinal passage for the introduction and pressure injection into the subjacent space of a hard-setting plastic composition, as will be hereinafter explained. For those purposes piping 16 and 16a having a conical end flange 17 and an intermediate barrier flange 19 is introduced into the hole 12. Openings 18 are provided in flange 17. The second flange 19 is secured to pipe 16 well above the bottom of the hole and forms a transverse partition or barrier across the hole to define the bottom of the concrete column. Where a strata 13 of sandy loam, mud or other earth substance unsuitable to afford support is present, the partition flange 19 is located above that strata. Otherwise, flange 19 is desirably located from 18 to 30 inches above the bottom of the hole.

Steel re-enforcing rods 20 are placed in the hole 12 and into the lateral opening 15. Thereafter concrete is introduced into the opening, around pipe 16, to fill the portion of the hole above the barrier flange 19, to a small distance above the foundation 11. The concrete is then allowed to harden with a sufiioient curing period for adequate strength.

The described installation thereafter is ready for the formation of an enlarged footing on the lower end of the column and, concomitantly, the stabilizing and lifting stages of the process. Such is accomplished by injecting, by suitable pumping apparatus, a plastic, hard-setting composition into the cavity below the column, through pipe 16. Such an apparatus, indicated generally at 22, FIG. 1, is known in the trade as a mud-jack. Its particular construction does not comprise a part of the present invention. Any suitable hydraulic apparatus capable of exerting sufficient pressure on the plastic composition will serve the purposes of the invention. Briefly, the implement 22 includes a hopper 23a the bottom of which slopes toward one end and there communicates with a pumping chamber 23 containing a reciprocating power-driven piston or plunger 24. The pumping chamber discharges into a horizontal pipe section 26 though a cut-off valve 27 and from there through a coupling sleeve 31 to the pipe 16.

A plastic composition suitable for the purpose hereof is made by mixing loose top soil or silty loam, comparatively free from sand, with water to form a. thin mud. A small percentage of cement (about 5%) is added for settling purposes and to reduce shrinkage of the mud. The composition is forced through the described piping, discharging through the openings 18 in the flange 17. The pumping operation is continued to insure the mudcement mixture filling the cavity below the concrete column 2 1, including all voids and fissures in the sides of the bore below the column. After the cavity voids and fissures become filled, and pumping continues, the plastic composition exerts great pressure in all directions on the surfaces of the hole below the column. This results in a compacting of the soil at the sides of the cavity below the column, and the enlargement of that cavity. With continued pumping, and after the earth at the base of the column will yield no further, pressures on the lower end of the column become sufiicient to raise the same, and with it the foundation resting on the shoulder 30.

When the structure has been raised to the desired level valve 27 is closed to trap and confine the composition under pressure within and below the column. Following the elapse of suflicient time to allow the composition to harden the pipe connecting the column to the pumping apparatus is disconnected at the joint 31. Thereafter the opening 32 above the column may be filled with soil up to grade level.

Where a foundation wall is to be raised by the described process by means of a series of columns, formed as heretofore described and as appears in FIG. 2, suitable transverse piping 33 is provided to connect the upper ends of all pipes 16 in the column, and the mud composition is pumped through, and pressure applied to all columns simultaneously, so that equal lifting forces and uniform upward displacement of the columns will be obtained.

It has been found that by ending the concrete portion of the column a susbtant-ial distance above the bottom of the bore, a much large-r and stronger footing for the column will be obtained. By partitioning the bore so as to end the concrete column above a faulty subsoil zone, and so as to enable the pressurized plastic material to penetrate fissures and stabilize the ground an appreciable distance below the end of the concrete column, affords a much stronger and more stable underpinning than any heretofore produced by injection methods.

The location of the partition member 19 that defines the bottom of the concrete column 21 is determined when the hole 12 is being dug. Where the driller encounters a water pocket, mud seam or a layer of sandy loam the partition 19 will be placed about a foot above the top of such faulty layer. As has been explained, excavation is desirably continued to provide a cavity that extends through the faulty layer.

In the present example the partition member 19 is secured as by welding it to a pipe nipple 34 to which is threaded the end of a pipe section 16, cut to length to place the partition 19 at the desired location in the bore. The footing member 17 is connected to the lower end of the terminal pipe section 16a, which is threaded into the lower end of the nipple 34. Pipe section 16a is of appropriate length for seating on firm bearing soil. It provides reenforcement for the base or footing material and mechanically ties the same to the column proper.

Where a seam of extremely wet soil is encountered below the bearing layer, such as might dilute and prevent proper setting of the plastic mixture, it is desirable to remove as much as possible of such water and wet soil before the plastic mixture is introduced into the cavity below the concrete column. In such instances it is desirable to utilize the system illustrated in FIGS. 5, 6 and 7 wherein a partition member 19a is provided with a second opening 40 to receive a return pipe 41, that terminates at the member (19a. A valve 42, FIG. 5, is installed in this pipe above the ground level.

In the operation of the alternate system, after the concrete column has been formed and has hardened as heretofore described, plastic mixture is pumped into the cavity below the column through pipe 16- and 16a. The plastic mixture, heavy with its cement content, fills the cavity below the column, displacing water and soft mud therefrom through the second pipe 41. Pumping is continued until the plastic mixture is discharged from pipe 41. Thereafter, valve 42 is closed and pumping continued until pressures suflicien-t to elevate the concrete column are attained. If it is desired to raise the column and the foundation resting thereon, pumping is continued until the foundation is raised to the desired level. Valve 27 is then closed to maintain the plastic material under pressure while it hardens. After this occurs the upper end portions of pipes 16 and 41 are removed and any cavity above the concrete column is filled with earth.

With reference to FIG. 2, it will be understood that one or more columns can be simultaneously pumped to obtain a stabilizing of the subsoil heretofore described and a raising of a foundation to restore it to an original position.

Having described my invention, I claim:

11. The method of underpinning a foundation structure which includes the steps of forming a substantially vertical hole adjacent the foundation, and forming a lateral opening from the hole under the foundation, casting a hollow concrete column in said hole with the lower end of said column spaced a substantial distance above the bottom of the hole, the column including a shoulder in the lateral opening and under the foundation, forming a base or footing at the lower end of said column by injecting firm-setting plastic material through the column and into the space therebelow, continuing said injection process until the space is filled and pressure is sufficient to displace the column, and allowing said material to solidify while being held under pressure.

2. The method of stabilizing a foundation structure comprising the steps of excavating to form a substantially vertical hole adjacent the foundation, of a depth to reach dovwiwardly to a solid, load-bearing strata, and forming a lateral opening from the hole under the foundation, installing a transverse partition member in said hole at a point spaced above the lower end thereof, introducing a pipe and concrete into the hole above said partition member to form a hollow concrete column that terminates downwardly at said partition member, the column including a shoulder in the lateral opening and under the foundation, injecting a firm-setting cementitious material through the hollow column and partition member and into the space below said column until said space is completely filled, expanding the filled space below the column by applying pressure to said material sufficient to displace the column, and maintaining said material under pressure until it has solidified.

3. The method of stabilizing a foundation, comprising the steps of drilling a substantially vertical hole in the earth adjacent the foundation of a depth to reach a strata having favorable load-bearing characteristics, and forming a lateral opening from the hole under the foundation, installing a transverse partition member in said hole a substantial distance above the lower end thereof, and installing a substantially vertical pipe from the upper end of the hole to and through said partition member, filling the hole above said partition member with concrete to form a hollow column including a shoulder in the lateral opening and under the foundation, injecting firm-setting cementitious material through the column to fill the space therebelow, and applying pressure on said material to displace the column, and thereafter allowing said cementitious material to solidify under pressure.

4. The method of underpinning and raising a foundation which comprises the steps of forming a bore hole in the ground adjacent to the foundation and reaching downwardly to a strata of solid earth, and forming a lateral opening from the hole under the foundation, forming a hollow concrete column by inserting a pipe and a par-tition member into said hole such that the pipe extends to the bottom of the hole and the partition member is spaced a substantial distance above the hole bottom, filling the hole above said partition member and around said pipe with concrete, and introducing cement into the lateral opening to form an integral shoulder under the foundation, allowing the concrete to harden, pumping a firmsetting cementitious material through said pipe to fill the space below said partition member, and continuing the pumping operation aforesaid to displace the column upwardly, and sustaining the pressure on said material until the same has solidified.

5. The method of underpinning a foundation which comprises the steps of drilling to form a substantially vertical hole in the earth adjacent to the foundation, and

forming a lateral opening from the hole under the f0undation, inserting two pipes vertically in said hole, one thereof extending substantially to the bottom of the hole and a second terminating at a point spaced a substantial distance above said hole bottom, installing a transverse partition member across the hole and around both pipes, located at the lower end of the second pipe, filling the hole and the lateral opening above said partition member with concrete, allowing the concrete to solidify to form a column with an integral shoulder under the foundation, pumping a firm-setting cementitious mixture through the first pipe to fill the hole below said partition member while allowing any fluid material in said hole to discharge through the second pipe, thereafter closing the passage 6 through said second pipe and continuing the pumping of said cementitious mixture to increase the pressure thereof in the hole below said partition member to displace the column upwardly, and allowing said cementitious mixture to solidify under said pressure.

References Cited by the Examiner UNITED STATES PATENTS 4/1895 Harris 61-50 9/1912 O Rourke 6 1--50 

1. THE METHOD OF UNDERPINNING A FOUNDATION STRUCTURE WHICH INCLUDES THE STEPS OF FORMING A SUBSTANTIALLY VERTICAL HOLE ADJACENT THE FOUNDATION, AND FORMING A LATERAL OPENING FROM THE HOLE UNDER THE FOUNDATION, CASTING A HOLLOW CONCRETE COLUMN IN SAID HOLE WITH THE LOWER END OF SAID COLUMN SPACED A SUBSTANTIAL DISTANCE ABOVE THE BOTTOM OF THE HOLE, THE COLUMN INCLUDING A SHOULDER IN THE LATERAL OPENING AND UNDER THE FOUNDATION, FORMING A BASE OR FOOTING AT THE LOWER END OF SAID COLUMN BY INJECTING FIRM-SETTING PLASTIC MATERIAL THROUGH THE COLUMN AND INTO THE SPACE THEREBELOW, CONTINUING SAID INJECTION PROCESS UNTIL THE SPACE IS FILLED AND PRESSURE IS SUFFICIENT TO DISPLACE THE COLUMN, AND ALLOWING SAID MATERIAL TO SOLIDIFY WHILE BEING HELD UNDER PRESSURE. 